Back to EveryPatent.com
United States Patent |
5,653,360
|
Brandhorst
,   et al.
|
August 5, 1997
|
Device for emptying a film tube
Abstract
For emptying a film tube 15 containing a flowable substance, the front end
f the tube is provided with a ring 17 the peripheral portion 19 of which
exceeds the inner diameter of a cartridge 1 which receives the tube 15.
The ring 17 has a conical sealing surface 20 which cooperates with a
sealing edge 12 formed inside the cap 2. In operation, the cylindrical
rear portion 7 of the cap 2 is slid onto a front portion 4 of the
cartridge 1, whereby the ring 17 provided on the tube 15 has its sealing
surface 20 centered and aligned in the radial and axial directions to
ensure proper engagement between the sealing edge 12 and the sealing
surface 20.
Inventors:
|
Brandhorst; Gerd (Landsberg, DE);
Herold; Wolf-Dietrich (Seefeld, DE);
Heiduczek; Ralf (Grobenzell, DE)
|
Assignee:
|
Thera Patent GmbH & Co. KG Gesellschaft fur Industrielle Schutzrechte (Seefeld, DE)
|
Appl. No.:
|
574697 |
Filed:
|
December 19, 1995 |
Foreign Application Priority Data
| Jan 13, 1994[DE] | 9400524 U |
Current U.S. Class: |
222/95; 222/326 |
Intern'l Class: |
B65D 035/28 |
Field of Search: |
222/95,105,326,327,386,386.5
|
References Cited
U.S. Patent Documents
2477875 | Aug., 1949 | Hutchason | 222/95.
|
3815787 | Jun., 1974 | Spies | 222/95.
|
5069364 | Dec., 1991 | McGill | 222/326.
|
5150820 | Sep., 1992 | McGill | 222/326.
|
5286105 | Feb., 1994 | Herold et al. | 366/177.
|
5322122 | Jun., 1994 | Jennings, Jr. | 166/307.
|
5501368 | Mar., 1996 | Brandhorst et al. | 222/95.
|
Foreign Patent Documents |
2186544 | Aug., 1987 | GB | 222/95.
|
Primary Examiner: Derakshani; Philippe
Attorney, Agent or Firm: Foley & Lardner
Parent Case Text
This is a continuation of Ser. No. 371,219, filed Jan. 11, 1995, now U.S.
Pat. No. 5,501,368.
Claims
We claim:
1. A device for emptying a film tube which contains a flowable substance
and has a dispensing end provided with a ring, the device comprising a
cylindrical housing with a displaceable piston and a cap and being adapted
to receive the tube between said piston and said cap, said housing having
an inner diameter and including an end portion having a ring support
surface, the cap having a dispensing opening, an annular engaging portion
surrounding the dispensing opening and cooperating with said ring for
sealing the dispensing end of the tube, and a cylindrical end portion
adapted to engage the end portion of the housing, said ring having a
peripheral portion which exceeds the inner diameter of the housing for
engaging said ring supporting surface, and wherein
a gap remains between mutually facing surfaces of said end portions of the
housing and the cap when said housing, cap and tube are assembled with
said ring abutting said engaging portion of the cap and the peripheral
portion of said ring abutting said supporting surface of said housing.
2. The device of claim 1, wherein the end portion of the cap surrounds the
end portion of the housing, said ring supporting surface being formed by
an end edge of the housing.
3. The device of claim 1, wherein said ring has a conical sealing surface
and said engaging portion or said cap is formed by an annular edge of said
cap.
4. A device for emptying a film tube which contains a flowable substance
and has a dispensing end provided with a ring, the device comprising a
cylindrical housing having an end portion, a displaceable piston and a cap
and being adapted to receive the tube between said piston and said cap,
the cap having a dispensing opening and an annular engaging portion
surrounding the dispensing opening and cooperating with said ring for
sealing the dispensing end of the tube, the housing having a ring
supporting surface which faces the cap, and the ring having a peripheral
portion which exceeds the inner diameter of the housing for engaging said
ring supporting surface, the end portion of the housing being further
formed with an annular shoulder, said cap having an edge portion facing
said annular shoulder, the housing and the cap being so dimensioned in the
moving direction of said piston that a play is retained between said
annular shoulder and said edge portion when said ring abuts said annular
engaging portion of the cap and the peripheral portion of said ring abuts
said ring supporting surface.
5. The device of claim 4, wherein the end portion of the housing has an
inner wall and the end portion of the cap has an inner wall, the
peripheral portion of the ring being centered by the inner wall of the
outer one of said two end portions.
Description
BACKGROUND OF THE INVENTION
A device for emptying a film tube containing a flowable substance is known
from U.S. Pat. No. 5,332,122, wherein the dispensing end of the tube
carries a ring having a conical sealing surface, the device including a
cylindrical housing for receiving the film tube between a displaceable
piston and a cap. A dispensing opening is provided in the cap which has an
annular surface for engaging the conical sealing surface of the ring
mounted on the tube.
For operating the known device, the film tube is inserted into the
cylindrical housing from the front or rear end thereof, whereupon the cap
is connected to the front end of the housing and the piston is inserted
into the rear end. At this time, the conical sealing surface of the ring
comes into contact with an engaging portion provided in the cap, which is
intended to make sure that the tube, which has been cut open at a position
beyond the ring, can be emptied only through the dispensing opening of the
cap while preventing any material from reaching the space between the cap,
the tube and the container. Since the sealing force is derived from the
dispensing pressure produced by advancement of the piston, it is
automatically increased whenever dispensing pressure is applied.
Proper operation of the known device requires the ring to be correctly
mounted on the film tube in the radial and angular directions. Since the
tube is manufactured from a length of tubular sheet material and has its
ends simply squeezed and sealed by clips, inaccuracies in mounting the
ring on the crimped tube end by means of adhesive cannot be avoided. In
practice there will be cases where the ring and thus its conical sealing
surface are disposed obliquely or eccentrically with respect to the axis
of the sealing counter surface provided in the cap. This may result in
incomplete sealing.
If the tube contains a substance of relatively low viscosity, such as a
fresh catalyst, there is a chance for the substance to start flowing out
even at low pressure exerted on the piston and before a sufficient
pressure has been established between the sealing surfaces of the ring and
the cap. In this situation, the escaping substance may reach the area of
the sealing surfaces and eventually prevent a sufficient seal.
It may further happen in practice that the outer diameter of the film tube
is at its upper tolerance limit, or that the outer surface of the tube or
the inner surface of the cylindrical housing is polluted. In this case, if
the tube is inserted into the housing from the rear, it may become jammed
and may not reach its foremost position, so that the sealing surface of
the ring does not reach the counter surface of the cap. The same may
happen when the tube is inserted from the front and is moved too far into
the housing. No proper sealing is ensured in these cases.
The described seal at the front end of the film tube is of particular
significance when the tube contains one of two or more components which
are simultaneously dispensed to prepare a mixture of substances. In such a
case, an exact mixing ratio is essential to achieve a finished material of
desired properties; this requires a predetermined quantity of each
component to be dispensed completely.
A further reason why the seal is important is the fact that in dispensing
devices of the type under consideration, only the tube is designed as a
disposable item whereas the housing and the cap should be parts of a
re-usable device. Pollution of the interior of the housing and of the rear
area of the cap may render these parts of the device useless.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a device for emptying a film
tube in which the seal between the front end of the tube and the cap is
ensured to an even greater extent than heretofore.
This object is met by a device for emptying a film tube which contains a
flowable substance and has a dispensing end provided with a ring, the
device comprising a cylindrical housing with a displaceable piston and a
cap and being adapted to receive the tube between the piston and the cap,
the cap having a dispensing opening and an annular engaging portion
surrounding the opening and cooperating with the ring for sealing the
dispensing end of the tube, wherein the housing has a supporting surface
which faces the cap and the ring has a peripheral portion which exceeds
the inner diameter of the housing for engaging the supporting surface.
As a result of the ring being made larger than the inner diameter of the
housing, the film tube may be inserted into the housing only from the
dispensing end thereof. When the housing and the cap are subsequently
locked together, engagement between the sealing surfaces provided on the
ring and the cap is automatically ensured. If the tube is jammed within
the housing and therefore cannot be completely inserted, all that may
happen is that the housing and the cap cannot be interlocked which will be
readily discovered.
Further, the ring is automatically aligned by virtue of its peripheral zone
engaging a supporting surface of the housing which faces the cap, even in
case the ring should have been adhered to the tube in a slanting way. When
the container and cap are interlocked, the ring is forced into position by
the sealing surface bearing against the annular abutment provided in the
cap, on the one hand, and the peripheral zone of the ring bearing against
the supporting surface of the housing, on the other hand.
In a preferred embodiment, an end portion of the housing and a cylindrical
end portion of the cap are adapted to engage each other, the peripheral
portion of the ring being centred by the inner wall of the outer one of
the two end portions. This results in the advantage that the ring is
automatically centred when the housing and the cap are fitted together,
whereby the conical sealing surface of the ring is precisely aligned with
the counter surface of the cap.
In another embodiment, the end portions of the housing and the cap have
such axial dimensions that a play is retained between their mutually
facing surfaces when the ring abuts the engaging portion of the cap and
the peripheral portion of the ring abuts the supporting surface of the
housing. This ensures that the pressure which is exerted on the rear end
of the tube when the piston is advanced, is utilised to produce a sealing
force between the ring and the cap even when the film tube becomes jammed
in the interior of the housing. In such a case, the play existing between
the housing and the cap permits the tube exposed to the pressure to
entrain the housing to such an extent that the sealing force is safely
produced.
Preferably, the ring has a conical sealing surface and the engaging portion
is formed by an annular edge of the cap. A high sealing pressure is
achieved due to the small area of contact between the ring and the cap.
BRIEF DESCRIPTION OF THE DRAWING
A preferred embodiment of the invention will now be explained in detail by
reference to the drawing which shows a longitudinal section through an
emptying device with a film tube inserted.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
According to the drawing, the device consists of a cylindrical cartridge 1
which constitutes the housing referred to above and in the claims, a
substantially rigid cap which placed on the front end (the lower end in
the drawing) of the cartridge 1, and a piston 3 inserted in the cartridge
from the rear end thereof for movement therein. The cartridge 1 is
manufactured from a length of stiff cylindrical tube of uniform inner
diameter and made of synthetic material, and has a front end portion 4 of
reduced outer diameter which forms a front edge 5 of the cartridge 1 and
an outer annular shoulder 6.
The cap 2 has a hollow cylindrical end portion 7 which forms a rear edge 8
and in the assembled condition surrounds the end portion 4 of the
cartridge 1. The cap 2 is perforated to form a dispensing opening 9 which
at its rear end begins with a conical inlet 10 and at its front end
terminates in a nozzle 11. The rear end of the inlet 10 forms an annular
sealing edge 12 (which in practice is a small sealing surface) coaxial
with the axis of the cartridge 1.
The drawing shows a soft-flexible film tube 15 inserted in the cartridge 1,
the rear end of which is shown as closed by a clip 16. The tube 15
contains a more or less viscous substance which, in a typical application,
may be a dental impression mass. The piston 3 has an axial recess 13 to
receive the crimped portion of the tube 15 extending beyond the clip 16.
The piston 3 thus has a forward directed annular portion 14 that bears
against the rear end of the tube 15.
In the drawing, the rear end of the film tube 15 is shown as already
somewhat compressed, although the piston 3 is shown in a retracted
position. This representation, while not showing an actual operating
condition, has been chosen for clarity.
The front end of the film tube 15 carries a ring 17 which has its rearward
facing edge glued to the tube 15. The ring 17 has an outward flange 18 the
peripheral portion 19 of which has an outer diameter that exceeds the
inner diameter of the cartridge 1. The front end of the ring 17
constitutes a forward tapering conical sealing surface 20.
In operation of the device, a film tube 15, which is filled with a
substance to be dispensed, is inserted into the cartridge 1 from the front
end thereof until the peripheral portion 19 of the ring flange 18 abuts
the front edge 5 of the cartridge 1. The end of the tube 15, which extends
forward through the ring 17 and is shaped similar to its rear end is cut
off together with a clip provided on the front end.
The cap 2 is then placed on the cartridge 1 with its end portion 7
surrounding the end portion 4 of the cartridge 1 so that the sealing edge
12 formed by the inlet 10 engages the sealing surface 20 of the ring 17.
The end portions 4 and 7 of the cartridge 1 and the cap 2 are dimensioned
so that in the assembled condition a gap remains between the shoulder 6
and the rear edge 8. Similarly, the front of the ring 17 and the rear side
of the cap 2 are so shaped and dimensioned that an air space remains in
front of the ring 17 outside the conical sealing surface. This ensures the
cartridge 1, the cap 2 and the ring 17 to engage each other in the
described way when the cap 2 is locked to the cartridge 1. While no
locking means have been shown in the drawing they may be constituted, for
instance, by placing the cartridge 1 with the cap 2 and the tube 15 in a
correspondingly designed apparatus which includes a drive for the piston
3. An apparatus of this type is described in U.S. Pat. No. 5,286,105.
Should the ring 17 be glued to the film tube 15 in a slanting way, it will
be automatically aligned by the peripheral portion 19 engaging the front
edge 5 of the cartridge 1. Further, any radial displacement of the ring 17
will be compensated by the inner surface of the end portion 7 of the cap
2. To achieve this compensation, the outer diameter of the ring flange 18
is only slightly smaller than the inner diameter of the end portion 2
thereby providing a guiding effect. When the cap 2 is placed on the
cartridge 1 and locked thereto, the conical sealing surface provided on
the ring 17 is automatically aligned with the sealing edge 12 provided in
the cap 2.
When pressure is subsequently exerted on the rear end of the tube 15 by the
advancing piston 3, this pressure is transmitted forward through the tube
15 and is available there as sealing pressure. Should the tube 15 become
jammed inside the cartridge 1 it will tend to move the cartridge 1 when
the piston 3 is advanced. At this time, the gap provided between the end
edge 8 and the shoulder 6 permits such a (small) movement that the
described sealing pressure is attained.
In case the tube 15 cannot be fully inserted into the cartridge 1 due to
excess manufacturing tolerance or due to pollution or in case foreign
matter should have become included in the sealing area, locking between
the cartridge 1 and the cap 2 will be impossible and this will be
recognized before the device is actuated.
Only a single cartridge has been shown in the drawing. This cartridge may
be part of a paired arrangements as provided in the device disclosed in
U.S. Pat. No. 5,286,105. For the same reason, the dispensing nozzle 11 is
offset laterally from the axis. As initially stated, exact and complete
dispensing of material in accordance with the advancement of the piston is
essential particularly in such double or multiple arrangements for
producing mixtures of components.
Top